NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-19 T13:21:25 PDT
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For refcode 2003MNRAS.340.1298R:
Retrieve 22 NED objects in this reference.
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NED Abstract

Copyright by Royal Astronomical Society. 2003MNRAS.340.1298R Is there a disc in the superluminal quasars? Rokaki, E.; Lawrence, A.; Economou, F.; Mastichiadis, A. Abstract. We look for the expected signature of an accretion disc by examining the properties of the H{alpha} emission line versus viewing angle in a sample of 22 superluminal (SL) quasars. The Doppler factor {delta}, jet velocity {gamma} and viewing angle {theta} towards the jet are derived from published radio and X-ray data. Most of the H{alpha} spectra (14) have been observed at the United Kingdom Infrared Telescope (UKIRT) and are reported here. About a quarter of the SL objects have weak or absent H{alpha} emission lines, with small equivalent widths (EW). These have high optical polarization, radio core dominance and Doppler factor, and most of them have high apparent SL velocity and low viewing angles. Therefore these weak-EW objects almost certainly have relativistically beamed optical continua. The strong-EW objects also show a clear beaming effect, but a much weaker one, with line EW varying by only a factor of 3 while radio core dominance varies by a factor of several hundred. The correlation of EW with {theta} is quantitatively in good agreement with the prediction of a flat accretion disc with limb darkening. The weak- and strong-EW sources also show an anticorrelation of line velocity width with the various beaming indicators. Again, the correlation with the derived viewing angle {theta} shows a quantitative agreement with the effect expected for an axisymmetric structure with velocity dominated by rotation. The line emission cannot come from the surface of the disc, or the line beaming would cancel the continuum beaming. However, it could come from an axisymmetric system of clouds corotating with the accretion disc. Keywords: accretion, accretion discs, galaxies: active, quasars: emission lines, quasars: general, radio continuum: galaxies
Retrieve 22 NED objects in this reference.
Please click here for ADS abstract

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